Material Handling Robot

ABSTRACT

An apparatus including a controller; a robot drive; a robot arm connected to the robot drive, where the robot arm has links including an upper arm, a first forearm connected to a first end of the upper arm, a second forearm connected to a second opposite end of the upper arm, a first end effector connected to the first forearm and a second end effector connected to the second forearm; and a transmission connecting the robot drive to the first and second forearms and the first and second end effectors. The transmission is configured to rotate the first and second forearms relative to the upper arm and rotate the first and second end effectors on their respective first and second forearms. The upper arm is substantially rigid and movement of the upper arm by the robot drive moves both the first and second forearms in opposite directions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 16/818,408,filed Mar. 13, 2020, which is a continuation of application Ser. No.16/104,529 filed Aug. 17, 2018, which claims priority under 35 USC119(e) to provisional patent application No. 62/548,064 filed Aug. 21,2017, and provisional patent application No. 62/546,677 filed Aug. 17,2017 which are hereby incorporated by reference in their entireties.

BACKGROUND Technical Field

The exemplary and non-limiting embodiments relate generally to amaterial-handling robot and, more particularly, to a material-handlingrobot with multiple end-effectors suitable such as for applications insemiconductor wafer processing systems.

Brief Description of Prior Developments

Material-handling robots, such as for applications in semiconductorwafer processing systems for example, are known. Some examples may befound in the following U.S. patents and patent publications (which arehereby incorporated by reference in their entireties): U.S. Pat. No.9,149,936 which discloses how non-circular pulleys may be calculated;U.S. Patent Publication No. US 2016/0167229 A1; and U.S. PatentPublication No. US 2017/0028546 A1.

SUMMARY

The following summary is merely intended to be exemplary. The summary isnot intended to limit the scope of the claims.

In accordance with one aspect, an example embodiment is provided in anapparatus comprising a controller comprising a processor and a memorycomprising computer code; a robot drive coupled to the controller, wherethe controller is configured to control actuation of the robot drive; arobot arm connected to the robot drive, where the robot arm compriseslinks including an upper arm, a first forearm connected to a first endof the upper arm, a second forearm connected to a second opposite end ofthe upper arm, a first end effector connected to the first forearm and asecond end effector connected to the second forearm; and a transmissionconnecting the robot drive to the first and second forearms and thefirst and second end effectors, where the transmission is configured torotate the first and second forearms relative to the upper arm androtate the first and second end effectors on their respective first andsecond forearms, where the upper arm is substantially rigid such thatmovement of the upper arm by the robot drive moves both the first andsecond forearms in opposite directions, where the controller and thetransmission are configured to coordinate movement and rotation of thelinks relative to one another to move the end effectors into and out ofa station comprising: moving the first forearm relative to the upperarm, while the upper arm remains substantially stationary, to move thefirst end effector into an entrance path of the station, andsubsequently rotating the upper arm and the first forearm to move thefirst end effector along the entrance path in a substantially straightline into the station.

In accordance with another aspect, an example method may compriseconnecting a controller to a robot drive; connecting an upper arm to afirst drive shaft of the robot drive; connecting a first forearm to anend of an upper arm; connecting a second forearm to an opposite end ofthe upper arm; connecting a first end effector to the first forearm;connecting a second end effector to the second forearm; connecting afirst transmission belt arrangement between a second drive shaft of therobot drive and the first forearm; connecting a second transmission beltarrangement between the first forearm and the first end effector, wherethe second transmission belt arrangement is configured to rotate thefirst end effector relative to the first forearm when the first forearmis rotated relative to the upper arm, where the controller and thetransmission belt arrangements are configured to coordinate movement ofthe upper arm and the first forearm on the upper arm relative to eachanother to move the first end effector into a station comprising: afirst path comprising moving the first forearm relative to the upperarm, while the upper arm remains substantially stationary, to move thefirst end effector into a starting location of a second entrance pathfor the station, and the second entrance path comprising subsequentlyrotating the upper arm and the first forearm on the upper arm to movethe first end effector along the second entrance path in a substantiallystraight line into the station.

In accordance with another aspect, an example method may comprise movinga first end effector along a first path from a first location to asecond location, where the second location is a start of a subsequentsecond substantially straight entrance path into a substrate processingmodule, where the first end effector is connected to an end of a firstforearm of a robot arm, where the first end effector is moved along thefirst path by rotating the first forearm on an upper arm of the robotarm by a robot drive while the upper arm remains substantiallystationary, and rotating the first end effector relative to the firstforearm as the first forearm is rotated on the upper arm, where therobot arm comprises a transmission belt arrangement connected betweenthe first end effector and the first forearm to automaticallymechanically rotate the first end effector relative to the first forearmas the first forearm is rotated on the upper arm; and moving the firstend effector from the second location into the substrate processingmodule along the second substantially straight entrance path, where thesecond substantially straight entrance path is maintained by rotatingthe upper arm by the robot drive to move the first forearm towards thesubstrate processing module and simultaneously rotating the firstforearm on the upper arm while the transmission belt arrangementautomatically mechanically rotates the first end effector relative tothe first forearm, as the first forearm is rotated on the upper arm, tomaintain the first end effector in a substantially straight line intothe substrate processing module.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features are explained in the followingdescription, taken in connection with the accompanying drawings,wherein:

FIG. 1A is a top view of an example embodiment of a robot;

FIG. 1B is a side view of the robot shown in FIG. 1A;

FIG. 2 is a diagram illustrating drive and transmission connections inthe robot shown in FIGS. 1A-1B;

FIGS. 3A-3B are diagrams illustrating example movement of the robot ofFIGS. 1-2 in a substrate processing system;

FIGS. 4A-4D are diagrams illustrating example movement of the robot ofFIGS. 1-2 in the substrate processing system shown in FIGS. 3A-3B;

FIG. 5A is a top view of an example embodiment of a robot;

FIG. 5B is a side view of the robot shown in FIG. 5A;

FIG. 6 is a diagram illustrating drive and transmission connections inthe robot shown in FIGS. 5A-5B;

FIGS. 7A-7B are diagrams illustrating example movement of the robot ofFIGS. 5-6 in a substrate processing system;

FIGS. 8A-8D are diagrams illustrating example movement of the robot ofFIGS. 5-6 in the substrate processing system shown in FIGS. 7A-7B;

FIG. 9A is a top view of an example embodiment of a robot;

FIG. 9B is a side view of the robot shown in FIG. 9A;

FIG. 10 is a diagram illustrating drive and transmission connections inthe robot shown in FIGS. 9A-9B;

FIGS. 11A-11B are diagrams illustrating example movement of the robot ofFIGS. 9-10 in a substrate processing system;

FIGS. 12A-12D are diagrams illustrating example movement of the robot ofFIGS. 9-10 in the substrate processing system shown in FIGS. 11A-11B;

FIG. 13A is a top view of an example embodiment of a robot;

FIG. 13B is a side view of the robot shown in FIG. 13A;

FIG. 14 is a diagram illustrating drive and transmission connections inthe robot shown in FIGS. 13A-13B;

FIGS. 15A-15B are diagrams illustrating example movement of the robot ofFIGS. 13-14 in a substrate processing system;

FIGS. 16A-16D are diagrams illustrating example movement of the robot ofFIGS. 13-14 in the substrate processing system shown in FIGS. 15A-15B;

FIGS. 17A-17D are diagrams illustrating example movement of the robot ofFIGS. 13-14 in the substrate processing system shown in FIGS. 15A-15B;

FIG. 18A is a top view of an example embodiment of a robot;

FIG. 18B is a side view of the robot shown in FIG. 18A;

FIG. 19 is a diagram illustrating drive and transmission connections inthe robot shown in FIGS. 18A-18B;

FIGS. 20A-20B are diagrams illustrating example movement of the robot ofFIGS. 18-19 in a substrate processing system;

FIGS. 21A-21E are diagrams illustrating example movement of the robot ofFIGS. 18-19 in the substrate processing system shown in FIGS. 20A-20B;

FIGS. 22A-22B illustrate some examples of circular and non-circularpulleys in belt/band transmissions; and

FIG. 23 is a diagram illustrating two different paths of movement of thefirst end effector shown FIGS. 21A-21C.

DETAILED DESCRIPTION OF EMBODIMENTS

Referring to FIGS. 1A-1B, an example embodiment of a robot 10 comprisingfeatures as described herein is shown. The robot 10 in this examplecomprises two end-effectors 12, 14 configured to support substrates Sthereon. In the various figures, the left end effector is shown with theindicator “A” and the right end effector is shown with the indicator“B”. FIG. 1A shows a top view of the robot 10 and FIG. 1B depicts a sideview of the robot 10. The robot 10 comprises of a robot drive unit 16and a robot arm 18. The drive unit 16 is coupled to a controller 19which may comprise, for example, at least one processor 21 and at leastone memory 23 comprising computer code 25 for controlling the drive 16and receiving sensor signals from sensors in the drive 16 as well asother sensors and inputs (not shown). Although features will bedescribed with reference to the example embodiments shown in thedrawings, it should be understood that features can be embodied in manyalternate forms of embodiments. In addition, any suitable size, shape ortype of elements or materials could be used.

The robot arm 18 comprises an upper arm 20, a left forearm 22 with theleft end-effector 12 and a right forearm 24 with the right end-effector14. Referring also to FIG. 2, the robot arm may be driven by the robotdrive unit 16. In this example embodiment, the robot drive unit 16comprises a three-axis spindle with three coaxial shafts; an outer T1shaft, a middle T2 shaft and an inner T3 shaft. The robot drive unit 16comprises three motors 17 a, 17 b, 17 c for axially rotating the driveshafts T1, T2, T3.

The upper arm 20 of the robot arm 18 may be attached directly to the T1shaft. The left forearm 22 may be coupled to the upper arm 20 via arotary joint (elbow joint 26), and actuated by the T2 shaft using a beltarrangement 28. The belt arrangement 28 may comprise a shoulder pulley30, which may be attached to the T2 shaft, elbow pulley 32, which may beattached to the left forearm 22, and a band, belt or cable 34, which maytransmit motion between the two pulleys 30, 32. The belt arrangement mayfeature a constant or variable transmission ratio. As an example, avariable transmission ratio may be implemented using non-circularpulleys.

Similarly, the right forearm 24 may be coupled to the upper arm 20 via arotary joint (elbow joint 36), and its orientation may be controlled bythe T3 shaft using another band, belt or cable arrangement 38. The beltarrangement 38 may comprise a shoulder pulley 40, which may be attachedto the T3 shaft, an elbow pulley 42, which may be attached to the rightforearm 24, and a band, belt or cable 44, which may transmit motionbetween the two pulleys 40, 42. Again, the belt arrangement 38 mayfeature a constant or variable transmission ratio, for example,implemented through the use of non-circular pulleys.

The T1, T2 and T3 shafts of the robot drive unit 16 may be rotated sothat the left end-effector A 12 and right end-effector B 14 can accessvarious stations ST, as illustrated diagrammatically in FIGS. 3 and 4,which show diagrams of the robot 10 in an example semiconductor waferprocessing system 2.

In order for the entire robot arm 18 to rotate, all drive shafts, i.e.,T1, T2 and T3, need to move in the desired direction of rotation of thearm by the same amount with respect to a fixed reference frame. This isdepicted diagrammatically by FIGS. 3A and 3B. In this particularexample, the entire robot arm 18 rotates in the clockwise direction by90 degrees.

In order for the left end-effector A to extend from the retractedposition shown in FIG. 4A to a station along a predefined path, such asa straight-line radial path, as depicted diagrammatically in the exampleof FIG. 4B, shafts T1 and T2 may rotate in a coordinated manner in theclockwise and counterclockwise directions, respectively. The inversekinematic equations for the left end-effector A 12 may be utilized todetermine the orientation of the T1 and T2 shafts as a function of theposition of the left end-effector A 12. As illustrated in FIG. 4B, theright end-effector B 14 may rotate out in sync with the upper arm 20 asthe left end-effector A 12 extends to the station ST 46. The leftend-effector A may be retracted by rotating the T1 and T2 shaftsbackward in a similar manner.

In order for the right end-effector B 14 to extend from the retractedposition of FIG. 4C to the same station ST 46 along a predefined path,such as a straight-line radial path, as depicted diagrammatically in theexample of FIG. 4D, shafts T1 and T3 may rotate in a coordinated mannerin the counterclockwise and clockwise directions, respectively, inaccordance with the inverse kinematic equations for the rightend-effector B 14. As illustrated in the FIG. 4D, the left end-effectorA 12 may swing out in sync with the upper arm 20 as the rightend-effector B extends to the station. The right end-effector B 14 maybe retracted by rotating the T1 and T3 shafts backward in a similarmanner.

The above operations may be utilized to pick/place a wafer from/to astation. A sequence of a pick operation with one end-effector followedby a place operation with the other end-effector may be used to quicklyexchange a wafer at a station (rapid exchange operation). As an example,the left end-effector A may be extended to a station, pick a wafer, andretract. The right end-effector B, which may carry another wafer, maythen extend to the same station, place the wafer, and retract.

The robot drive unit 16 may include a vertical lift mechanism to controlthe vertical elevation of the robot arm, which may be used to accessstations at different elevations, compensate for the vertical distancebetween the end-effectors of the robot arm if the end-effectors are notcoplanar, and facilitate material pick/place operations.

Although the illustrations of the example embodiment show the leftforearm of the robot driven by the T2 shaft and the right forearm of therobot driven by the T3 shaft, any suitable driving schemes andtransmission arrangements may be used. Similarly, while straight linesare used to represent the example embodiment in the figures, the upperarm, forearms and end-effectors may feature any suitable shapes, forinstance, to avoid interference with obstacles in the workspace of therobot.

Another example embodiment of a robot with two end-effectors is depicteddiagrammatically in FIGS. 5A-5B. FIG. 5A shows the top view of the robot50 and FIG. 5B depicts the side view of the robot 50. The robot 50comprises the robot drive unit 16 and a robot arm 52. The robot arm 52in this example features two linkages, i.e., a left linkage and a rightlinkage. The left linkage comprises a left upper arm 54 and a leftforearm 22 with a left end-effector A 12. Similarly, the right linkagecomprises a right upper arm 56 and a right forearm 24 with a rightend-effector B 14.

An example internal arrangement of the robot is depicteddiagrammatically in FIG. 6. The robot arm 52 is configured to be drivenby the robot drive unit 16 with a three-axis spindle with three coaxialshafts, e.g., an outer T1 shaft, a T2 shaft and an inner T3 shaft.

The left upper arm 54 of the robot arm 52 is shown attached directly tothe T1 shaft in this example. The left forearm 22 is coupled to the leftupper arm 54 via a rotary joint (left elbow joint) 26, and actuated bythe T2 shaft using the belt arrangement 28. The belt arrangement 28 inthis example comprises a left shoulder pulley 30, which may be attachedto the T2 shaft, a left elbow pulley 32, which may be attached to theleft forearm 22, and a band, belt or cable 34, which is configured totransmit motion between the two pulleys 30, 32. The belt arrangement 28may feature a constant or variable transmission ratio. As an example,the variable transmission ratio may be selected so that the orientationof the left forearm 22 with the left end-effector A 12 changes in apredefined manner as a function of the relative position of the leftupper arm and the T2 shaft. However, any other suitable arrangement maybe used.

Similarly, the right upper arm 56 of the robot arm 52 is shown attacheddirectly to the T3 shaft in this example. The right forearm 24 may becoupled to the right upper arm 56 via the rotary joint (right elbowjoint) 36, and actuated by the T2 shaft using the belt arrangement 38.The belt arrangement 38 may comprise the right shoulder pulley 40, whichmay be attached to the T2 shaft, the right elbow pulley 42, which may beattached to the right forearm 24, and the band, belt or cable 44, whichmay transmit motion between the two pulleys 40, 42. The belt arrangement38 may feature a constant or variable transmission ratio. As an example,the variable transmission ratio may be selected so that the orientationof the right forearm with the right end-effector B 14 changes in apredefined manner as a function of the relative position of the rightupper arm and the T2 shaft. However, any other suitable arrangement maybe used.

The T1, T2 and T3 shafts of the robot drive unit 16 may be rotated sothat the left end-effector A 12 and right end-effector B 14 can accessvarious stations ST, as illustrated diagrammatically in FIGS. 7 and 8,which show diagrams of the robot 50 in an example semiconductor waferprocessing system 3.

In order for the entire robot arm 52 to rotate, all drive shafts, i.e.,T1, T2 and T3, need to move in the desired direction of rotation of thearm by the same amount with respect to a fixed reference frame. This isdepicted diagrammatically in FIGS. 7A-7B. In this particular example,the entire robot arm 52 is shown rotated in the clockwise direction by90 degrees.

In order for the left end-effector A 12 to extend from the retractedposition of FIG. 8A to a station ST 46 along a predefined path, such asa straight-line radial path for example, as depicted diagrammatically inthe example of FIG. 8B, shaft T1 may rotate in the clockwise directionwhile shaft T2 may be held stationary. As illustrated in FIGS. 8A-8B,unlike the example shown in FIGS. 4A-4B, the right end-effector B 14 mayremain stationary as the left end-effector A 12 extends to the stationST 46. The left end-effector A 12 may be retracted by rotating the T1shaft backward in a similar manner.

In order for the right end-effector B 14 to extend from the retractedposition of FIG. 8C to the same station ST 46 along a predefined path,such as a straight-line radial path for example, as depicteddiagrammatically in the example of FIGS. 8C-8D, shafts T3 may rotate inthe counterclockwise direction while shaft T2 may be held stationary. Asillustrated, the left end-effector A 12 may remain stationary as theright end-effector B 14 extends to the station ST 46. The rightend-effector B 14 may be retracted by rotating the T3 shaft backward ina similar manner.

The above operations may be utilized to pick/place a wafer from/to astation. A sequence of a pick operation with one end-effector followedby a place operation with the other end-effector may be used to quicklyexchange a wafer at a station (rapid exchange operation). As an example,the left end-effector A 12 may be extended to a station, pick a wafer,and retract. The right end-effector B 14, which may carry another wafer,may then extend to the same station, place the wafer, and retract.

The robot drive unit 16 may include a vertical lift mechanism to controlthe vertical elevation of the robot arm 52, which may be used to accessstations at different elevations, compensate for the vertical distancebetween the end-effectors of the robot arm if the end-effectors are notcoplanar, and facilitate material pick/place operations.

Although the illustrations of the example embodiment show the robot 50with the left upper arm 22 below the right upper arm 24, and the leftand right end-effectors are depicted at the same elevation (coplanar),in alternate embodiments the upper arms and end-effectors may bearranged in various configurations and elevations. Similarly, althoughthe example embodiment shows the left upper 54 of the robot 50 driven bythe T1 shaft and the right upper arm 56 of the robot driven by the T3shaft, any suitable driving schemes and transmission arrangements may beused. Furthermore, while straight lines are used to represent theexample embodiment in the figures, the upper arms, forearms andend-effectors may feature any suitable shapes, for instance, to avoidinterference with obstacles in the workspace of the robot.

Another example embodiment of a robot with two end-effectors is depicteddiagrammatically in FIGS. 9A-9B. FIG. 9A shows a top view of a robot 60and FIG. 9B depicts a side view of the robot 60. The robot 60 maycomprise the robot drive unit 16 and a robot arm 62. The robot arm 62may feature two linkages, i.e., a left linkage and a right linkage.

The left linkage in this example comprises an upper arm 64, a leftforearm 66 and left wrist 68 with a left end-effector A 70. Similarly,the right linkage in this example comprises a upper arm 74, a rightforearm 76 and a right wrist 78 with a right end-effector B 80. Theupper arms 64, 74 of the left and right linkages are rigidly connectedtogether, and can be viewed as a single shared link 75.

An example internal arrangement of the robot 60 is depicteddiagrammatically in FIG. 10. The robot arm 62 may be driven by the robotdrive unit 16 with a three-axis spindle with three coaxial shafts, e.g.,an outer T1 shaft, a T2 shaft and an inner T3 shaft.

The upper arm link 75 of the robot arm 62 may be attached directly tothe T1 shaft. The left forearm 66 may be coupled to the upper arm link75 via a rotary joint (left elbow joint) 26, and actuated by the T2shaft using a belt arrangement 28. The belt arrangement 28 may comprisea left shoulder pulley 30, which may be attached to the T2 shaft, a leftelbow pulley 32, which may be attached to the left forearm 66, and aband, belt or cable 34, which may transmit motion between the twopulleys 30, 32.

The left wrist 68 with the left end-effector A 70 may be coupled to theleft forearm 66 via a rotary joint (left wrist joint) 82, androtationally constrained by another belt arrangement 84. The beltarrangement 84 may comprise a second left elbow pulley 86, which may beattached to the upper arm 64, a left wrist pulley 90, which may beattached to the left wrist 68, and a band, belt or cable 92, which maytransmit motion between the two pulleys 86, 90. The belt arrangement 84may feature a variable transmission ratio. As an example, the variabletransmission ratio may be selected so that the orientation of the leftwrist 68 changes in a predefined manner as a function of the relativeangle of the upper arm 64 and the left forearm 66. However, any othersuitable arrangement may be used.

The right linkage may be conceptually viewed as a mirror image of theleft linkage. The right forearm 76 may be coupled to the upper arm 74via a rotary joint (right elbow joint) 36, and actuated by the T3 shaftusing a belt arrangement 38. The belt arrangement 38 may comprise aright shoulder pulley 40, which may be attached to the T3 shaft, a rightelbow pulley 42, which may be attached to the right forearm 76, and aband, belt or cable 44, which may transmit motion between the twopulleys 40, 42.

The right wrist 78 with the right end-effector B 80 may be coupled tothe right forearm 76 via a rotary joint (right wrist joint) 94, androtationally constrained by another belt arrangement 96. The beltarrangement 96 may comprise a second right elbow pulley 98, which may beattached to the upper arm 74, a right wrist pulley 100, which may beattached to the right wrist 78, and a band, belt or cable 102, which maytransmit motion between the two pulleys 98, 100. The belt arrangement 96may feature a variable transmission ratio. As an example, the variabletransmission ratio may be selected so that the orientation of the rightwrist 78 changes in a predefined manner as a function of the relativeangle of the right upper arm 74 and the right forearm 76. However, anyother suitable arrangement may be used.

As an example, the variable-transmission belt arrangements may beconveniently designed so that, as the arm extends from its retractedposition to a station, the orientation of the end-effector graduallyaligns with the radial path to the station and then remains unchangedrelative to the radial path to the station. Consequently, the relativeorientation of the end-effector may be the same when the arm is extendedto stations in different radial locations.

The T1, T2 and T3 shafts of the robot drive unit may be rotated so thatthe left end-effector A and right end-effector B can access variousstations, as illustrated diagrammatically in FIGS. 11-12, which showdiagrams of the robot 60 in an example semiconductor wafer processingsystem 4.

In order for the entire robot arm to rotate, all drive shafts, i.e., T1,T2 and T3, need to move in the desired direction of rotation of the arm62 by the same amount with respect to a fixed reference frame. This isdepicted diagrammatically in FIGS. 11A-11B. In this particular example,the entire robot arm 62 rotates in the clockwise direction by 90degrees.

In order for the left end-effector A 70 to extend from the retractedposition of FIG. 12A to a station ST 46 along a predefined path, such asa straight-line radial path for example, as depicted diagrammatically inthe example of FIG. 12B, shaft T1 may rotate in the clockwise directionwhile shaft T2 may be held stationary. As illustrated in FIGS. 12A-12B,the right end-effector B 80 may rotate as the left end-effector A 70extends to the station ST 46. In an example embodiment thevariable-transmission belt arrangements may be conveniently designed sothat the orientation of the left end-effector does not change withextension over the final portion of the move, which means that therelative orientation of the end-effector may be the same when extendedto stations in different radial locations. The left end-effector A 70may be retracted by rotating the T1 shaft backward in a similar manner.

In order for the right end-effector B 80 to extend from the retractedposition of FIG. 12C to the same station along a predefined path, suchas a straight-line radial path for example, as depicted diagrammaticallyin the example of FIG. 12D, shafts T3 may rotate in the counterclockwisedirection while shaft T2 may be held stationary. As illustrated in thefigures, the left end-effector A 70 may rotate as the right end-effectorB 80 extends to the station ST 46. In an example embodiment thevariable-transmission belt arrangements may be conveniently designed sothat the orientation of the left end-effector does not change withextension over the final portion of the move, which means that therelative orientation of the end-effector may be the same when extendedto stations in different radial locations. The right end-effector B 80may be retracted by rotating the T3 shaft backward in a similar manner.

The above operations may be utilized to pick/place a wafer from/to astation ST. A sequence of a pick operation with one end-effectorfollowed by a place operation with the other end-effector may be used toquickly exchange a wafer at a station (rapid exchange operation). As anexample, the left end-effector A 70 may be extended to a station, pick awafer, and retract. The right end-effector B 80, which may carry anotherwafer, may then extend to the same station, place the wafer, andretract.

As depicted diagrammatically in FIG. 10, the robot drive unit mayinclude a vertical lift mechanism 104 to control the vertical elevationof the robot arm 60, which may be used to access stations ST atdifferent elevations, compensate for the vertical distance between theend-effectors of the robot arm if the end-effectors are not coplanar,and facilitate material pick/place operations.

Although the illustrations of the example embodiment show the robot 60with the left upper arm below the right upper arm, and the left andright end-effectors are depicted at the same elevation (coplanar), theupper arms and end-effectors may be arranged in various configurationsand elevations. Similarly, although the example embodiment shows theleft upper of the robot 60 driven by the T1 shaft and the right upperarm of the robot driven by the T3 shaft, any suitable driving schemesand transmission arrangements may be used. Furthermore, while straightlines are used to represent the example embodiment in the figures, theupper arms, forearms and end-effectors may feature any suitable shapes,for instance, to avoid interference with obstacles in the workspace ofthe robot.

Another example embodiment of a robot with two end-effectors is depicteddiagrammatically in FIGS. 13A-13B. FIG. 13A shows a top view of therobot 110 and FIG. 13B depicts a side view of the robot 110. The robot110 may consist of a robot drive unit 16 and a robot arm 112. The robotarm 112 may feature two linkages, i.e., a left linkage and a rightlinkage.

The left linkage in this example comprises a left upper arm 114, theleft forearm 66 and left wrist 68 with the left end-effector A 70.Similarly, the right linkage in this example comprises a right upper arm116, the right forearm 76 and the right wrist 78 with the rightend-effector B 80.

An example internal arrangement of the robot is depicteddiagrammatically in FIG. 14. The robot arm 112 may be driven by therobot drive unit 16 with a three-axis spindle with three coaxial shafts,e.g., an outer T1 shaft, a T2 shaft and an inner T3 shaft.

The left upper arm 114 of the robot arm 112 may be attached directly tothe T1 shaft. The left forearm 66 may be coupled to the left upper arm114 via a rotary joint (left elbow joint) 26, and actuated by the T2shaft using a belt arrangement 28. The belt arrangement 28 may comprisea left shoulder pulley 30, which may be attached to the T2 shaft, a leftelbow pulley 32, which may be attached to the left forearm, and a band,belt or cable 34, which may transmit motion between the two pulleys 30,32. The belt arrangement 28 may feature a variable transmission ratio.As an example, the variable transmission ratio may be selected so thatthe orientation of the left forearm 66 changes in a predefined manner asa function of the relative position of the left upper arm 114 and the T2shaft. However, any other suitable arrangement may be used.

The left wrist 78 with the left end-effector A 70 may be coupled to theleft forearm 66 via a rotary joint (right wrist joint), and rotationallyconstrained by another belt arrangement 84. The belt arrangement 84 maycomprise a second left elbow pulley 86, which may be attached to theleft upper arm 114, a left wrist pulley 90, which may be attached to theleft wrist 68, and a band, belt or cable 92, which may transmit motionbetween the two pulleys 86, 90. The belt arrangement 84 may feature avariable transmission ratio. As an example, the variable transmissionratio may be selected so that the orientation of the left wrist changesin a predefined manner as a function of the relative angle of the leftupper arm and the left forearm. However, any other suitable arrangementmay be used.

The right linkage may be conceptually viewed as a mirror image of theleft linkage. The right upper arm 116 of the robot arm 112 may beattached directly to the T3 shaft. The right forearm 76 may be coupledto the right upper arm 112 via a rotary joint (right elbow joint), andactuated by the T2 shaft using a belt arrangement 38. The beltarrangement 38 may comprise a right shoulder pulley 40, which may beattached to the T2 shaft, a right elbow pulley 42, which may be attachedto the right forearm, and a band, belt or cable 44, which may transmitmotion between the two pulleys 40, 42. The belt arrangement 38 mayfeature a constant or variable transmission ratio. As an example, thevariable transmission ratio may be selected so that the orientation ofthe right forearm changes in a predefined manner as a function of therelative position of the right upper arm and the T2 shaft. However, anyother suitable arrangement may be used.

Similarly, the right wrist 78 with a right end-effector B 80 may becoupled to the right forearm 76 via a rotary joint (left wrist joint),and rotationally constrained by another belt arrangement 96. The beltarrangement 96 may comprise a second right elbow pulley 98, which may beattached to the right upper arm 116, a right wrist pulley 100, which maybe attached to the right wrist 78, and a band, belt or cable 102, whichmay transmit motion between the two pulleys 98, 100. The beltarrangement 96 may feature a variable transmission ratio. As an example,the variable transmission ratio may be selected so that the orientationof the right wrist changes in a predefined manner as a function of therelative angle of the right upper arm and the right forearm. However,any other suitable arrangement may be used.

As an example, the variable-transmission belt arrangements may beconveniently designed so that, as the arm extends from its retractedposition to a station, the orientation of the end-effector graduallyaligns with the radial path to the station and then remains unchangedrelative to the radial path to the station. Consequently, the relativeorientation of the end-effector may be the same when the arm is extendedto stations in different radial locations.

The T1, T2 and T3 shafts of the robot drive unit may be rotated so thatthe left end-effector A and right end-effector B can access variousstations, as illustrated diagrammatically in FIGS. 15-16, which showdiagrams of the robot 110 in an example semiconductor wafer processingsystem 5.

In order for the entire robot arm 112 to rotate, all drive shafts, i.e.,T1, T2 and T3, need to move in the desired direction of rotation of thearm 112 by the same amount with respect to a fixed reference frame. Thisis depicted diagrammatically in FIGS. 15A-15B. In this particularexample, the entire robot arm 112 rotates in the clockwise direction by90 degrees.

In order for the left end-effector A 70 to extend from the retractedposition of FIG. 16A to a station ST 46 along a predefined path, such asa straight-line radial path for example, as depicted diagrammatically inthe example of FIGS. 16A-16B, shaft T1 may rotate in the clockwisedirection while shaft T2 may be held stationary. As illustrated in thefigures, the right end-effector B 80 may remain stationary as the leftend-effector A 70 extends to the station ST 46. Thevariable-transmission belt arrangements may be conveniently designed sothat the orientation of the left end-effector does not change withextension over the final portion of the move, which means that therelative orientation of the end-effector may be the same when extendedto stations in different radial locations. The left end-effector A 70may be retracted by rotating the T1 shaft backward in a similar manner.

In order for the right end-effector B 80 to extend from the retractedposition of FIG. 16C to the same station ST 46 along a predefined path,such as a straight-line radial path for example, as depicteddiagrammatically in the example of FIGS. 16C-16D, shafts T3 may rotatein the counterclockwise direction while shaft T2 may be held stationary.As illustrated in the figures, the left end-effector A 70 may remainstationary as the right end-effector B 80 extends to the station ST 46.The variable-transmission belt arrangements may be conveniently designedso that the orientation of the left end-effector does not change withextension over the final portion of the move, which means that therelative orientation of the end-effector may be the same when extendedto stations in different radial locations. The right end-effector B 80may be retracted by rotating the T3 shaft backward in a similar manner.

The extension motion from the retracted position of FIG. 16A to theextended position of FIG. 16B is further illustrated in FIGS. 17A-17D,which shows intermediate phases of the motion. FIGS. 17A-17D show thetwo different types of paths P1 and P2 which the substrate supportingarea SSA of the first end effector 70 travels between the retractedfirst position shown in FIG. 17A to the extended position inside thesubstrate processing module 46 shown in FIG. 17D. The first path P1 iscurved. The second path P2 is straight. In the first path P1 from FIG.17A to FIG. 17B the SSA is moved from the retracted first position shownin FIG. 17A to the start of the second path P2 shown in FIG. 17B. Fromthe start of the second path P2 shown in FIG. 17B, the SSA is then movedforward into the station 46 with the end effector 70 straightening outand the SSA traveling along the straight line of the second path P2.

The above operations may be utilized to pick/place a wafer from/to astation ST 46. A sequence of a pick operation with one end-effectorfollowed by a place operation with the other end-effector may be used toquickly exchange a wafer at a station (rapid exchange operation). As anexample, the left end-effector A 70 may be extended to the station ST46, pick a wafer, and retract. The right end-effector B 80, which maycarry another wafer, may then extend to the same station ST 46, placethe wafer, and retract.

As depicted diagrammatically in FIG. 14, the robot drive unit mayinclude a vertical lift mechanism 104 to control the vertical elevationof the robot arm 112, which may be used to access stations ST atdifferent elevations, compensate for the vertical distance between theend-effectors of the robot arm if the end-effectors are not coplanar,and facilitate material pick/place operations.

Although the illustrations of the example embodiment show the robot 110with the left upper arm below the right upper arm, and the left andright end-effectors are depicted at the same elevation (coplanar), theupper arms and end-effectors may be arranged in various configurationsand elevations. Similarly, although the example embodiment shows theleft upper arm of the robot 110 driven by the T1 shaft and the rightupper arm of the robot 110 driven by the T3 shaft, any suitable drivingschemes and transmission arrangements may be used. Furthermore, whilestraight lines are used to represent the example embodiment in thefigures, the upper arms, forearms and end-effectors may feature anysuitable shapes, for instance, to avoid interference with obstacles inthe workspace of the robot.

Another example embodiment of a robot with two end-effectors is depicteddiagrammatically in FIGS. 18A-18B. FIG. 18A shows a top view of therobot 120 and FIG. 18B depicts a side view of the robot 120. The robot120 in this embodiment comprises a robot drive unit 16 and a robot arm122. The drive unit 16 is coupled to a controller 19 which may comprise,for example, at least one processor 21 and at least one memory 23comprising computer code 25 for controlling the drive 16 and receivingsensor signals from sensors in the drive 16 as well as other sensors andinputs (not shown). The robot arm 122 may feature two linkages, i.e., aleft linkage and a right linkage.

The left linkage, in this example embodiment, comprises an upper arm 124a, the left forearm 66 and the left wrist 68 with the left end-effectorA 70. Similarly, the right linkage, in this example embodiment,comprises the upper arm 124 b, the right forearm 76 and the right wrist78 with the right end-effector B 80. In this example embodiment, theupper arms 124 a, 124 b of the left and right linkages are rigidlyconnected together, and can be viewed as a single shared link 124.

An example internal arrangement of the robot 120 is depicteddiagrammatically in FIG. 19. The robot arm 122 may be driven by a robotdrive unit 16 with a three-axis spindle with three coaxial shafts, e.g.,an outer T1 shaft, a T2 shaft and an inner T3 shaft.

The upper arm 124 of the robot arm 122 may be attached directly to theT1 shaft. The left forearm 66 may be coupled to the upper arm 124 via arotary joint (left elbow joint) 26, and actuated by the T2 shaft using abelt arrangement 28. The belt arrangement 28 may comprise a leftshoulder pulley 30, which may be attached to the T2 shaft, a left elbowpulley 32, which may be attached to the left forearm 66, and a band,belt or cable 34, which may transmit motion between the two pulleys 30,32.

The left wrist 68 with the left end-effector A 70 may be coupled to theleft forearm 66 via a rotary joint (left wrist joint) 82, androtationally constrained by another belt arrangement 84. The beltarrangement 84 may comprise a second left elbow pulley 86, which may beattached to the upper arm 124, a left wrist pulley 90, which may beattached to the left wrist 68, and a band, belt or cable 92, which maytransmit motion between the two pulleys 86, 90. The belt arrangement 84may feature a variable transmission ratio. As an example, the variabletransmission ratio may be selected so that the orientation of the leftwrist changes in a predefined manner as a function of the relative angleof the upper arm and the left forearm. However, any other suitablearrangement may be used.

The right linkage may be conceptually viewed as a mirror image of theleft linkage. The right forearm 76 may be coupled to the upper arm 124via a rotary joint (right elbow joint) 36, and actuated by the T3 shaftusing a belt arrangement 38. The belt arrangement 38 may comprise aright shoulder pulley 40, which may be attached to the T3 shaft, a rightelbow pulley 42, which may be attached to the right forearm 76, and aband, belt or cable 44, which may transmit motion between the twopulleys 40, 42.

The right wrist 78 with the right end-effector B 80 may be coupled tothe right forearm 76 via a rotary joint (right wrist joint) 94, androtationally constrained by another belt arrangement 96. The beltarrangement 96 may comprise a second right elbow pulley 98, which may beattached to the upper arm 76, a right wrist pulley 100, which may beattached to the right wrist 78, and a band, belt or cable 102, which maytransmit motion between the two pulleys 98, 100. The belt arrangement 96may feature a variable transmission ratio. As an example, the variabletransmission ratio may be selected so that the orientation of the rightwrist 78 changes in a predefined manner as a function of the relativeangle of the right upper arm 124 and the right forearm 76. However, anyother suitable arrangement may be used.

As an example, the variable-transmission belt arrangements 28, 38, 84,96 may be conveniently designed so that, as the arm extends from itsretracted position to a station, the orientation of the end-effectorchanges in a suitable predefined manner in the initial portion of theextension motion and then follows the radial path to the station in thefinal portion of the extension motion. More specifically, as an example,the variable-transmission belt arrangements may be designed so that, asthe arm extends from its retracted position to a station, theorientation of the end-effector remains substantially parallel with theradial path to the station until the forearm rotates directly above theupper arm and then follows the radial path to the station.

The T1, T2 and T3 shafts of the robot drive unit may be rotated so thatthe left end-effector A 70 and right end-effector B 80 can accessvarious stations, as illustrated diagrammatically in FIGS. 20-21, whichshow diagrams of the robot 120 in an example semiconductor waferprocessing system 6.

In order for the entire robot arm 122 to rotate, all drive shafts, i.e.,T1, T2 and T3, need to move in the desired direction of rotation of thearm 122 by the same amount with respect to a fixed reference frame. Thisis depicted diagrammatically in FIGS. 20A-20B. In this particularexample, the entire robot arm 122 rotates in the clockwise direction by90 degrees.

In order for the left end-effector A 70 to extend from the commonretracted position of FIG. 21A to the partially extended position ofFIG. 21B, shaft T2 may rotate in the counterclockwise direction whileshaft T1 may be held stationary. The variable-transmission beltarrangements may be conveniently designed so that the orientation of theleft end-effector 80 may remain parallel with the starting orientationand/or the radial path to the station ST 46 during the move to thepartially extended position of FIG. 21B. In order to complete theextension from the partially extended position of FIG. 21B to thestation ST 46 along a predefined path, such as a straight-line radialpath for example, as depicted diagrammatically in the example of FIG.21C, shafts T2 may rotate in the counterclockwise direction while shaftT1 may rotate in the clockwise direction. As illustrated in the figures,the right end-effector B 80 may rotate as the left end-effector A 70extends to the station ST 46. The left end-effector A 70 may beretracted by rotating the T1 and T2 shafts backward in a similar manner.

In order for the right end-effector B 80 to extend from the commonretracted position of FIG. 21A to the partially extended position ofFIG. 21D, shaft T3 may rotate in the clockwise direction while shaft T1may be held stationary. The variable-transmission belt arrangements maybe conveniently designed so that the orientation of the rightend-effector may remain parallel with the starting orientation and/orthe radial path to the station ST 46 during the move to the partiallyextended position of FIG. 21D. In order to complete the extension fromthe partially extended position of FIG. 21D to the station ST 46 along apredefined path, such as a straight-line radial path for example, asdepicted diagrammatically in the example of FIG. 21E, shafts T3 mayrotate in the clockwise direction while shaft T1 may rotate in thecounterclockwise direction. As illustrated in the figure, the leftend-effector A 70 may rotate as the right end-effector B 80 extends tothe station. The right end-effector B 80 may be retracted by rotatingthe T1 and T3 shafts backward in a similar manner.

The above operations may be utilized to pick/place a wafer from/to astation. A sequence of a pick operation with one end-effector followedby a place operation with the other end-effector may be used to quicklyexchange a wafer at the station (rapid exchange operation). As anexample, the left end-effector A 70 may be extended to the station, picka wafer, and retract. The right end-effector B 80, which may carryanother wafer, may then extend to the same station, place the wafer, andretract.

The extension motion from the retracted position of FIG. 21A to theextended position of FIG. 21C illustrates two different types of pathsP1 and P2 and motions which the substrate supporting area SSA of thefirst end effector 70 travels between the retracted first position shownin FIG. 21A to the extended position inside the substrate processingmodule 46 shown in FIG. 21C. Referring also to FIG. 23, the first pathP1 is straight, but may be curved as in the example shown in FIGS.17A-17D. The second path P2 is straight. In the first path P1 from FIG.21A to FIG. 21B the SSA is moved from the retracted first position shownin FIG. 21A to the start of the second path P2 shown in FIG. 21B. Fromthe start of the second path P2 shown in FIG. 21B, the SSA is then movedforward into the station 46 with the end effector 70 being straightduring the travel along the second path and the SSA traveling along thestraight line of the second path P2.

As depicted diagrammatically in FIG. 19, the robot drive unit 16 mayinclude a vertical lift mechanism 104 to control the vertical elevationof the robot arm 122, which may be used to access stations ST atdifferent elevations, compensate for the vertical distance between theend-effectors of the robot arm if the end-effectors are not coplanar,and facilitate material pick/place operations.

Although the illustrations of the example embodiment show the robot 120in the retracted position with the left and right end-effectors 70, 80oriented in a substantially parallel manner, any suitable orientation ofthe end-effectors may be used. Similarly, although the exampleembodiment shows the left forearm 66 of the robot driven by the T2 shaftand the right forearm 76 of the robot driven by the T3 shaft, anysuitable driving schemes and transmission arrangements may be used.Furthermore, while straight lines are used to represent the exampleembodiment in the figures, the upper arms, forearms and end-effectorsmay feature any suitable shapes, for instance, to avoid interferencewith obstacles in the workspace of the robot.

As noted above, any of the belt arrangement may feature a constant orvariable transmission ratio, for example, implemented through the use ofcircular and/or non-circular pulleys. FIGS. 22A-22B show some examplesof a circular pulley 200 and non-circular pulleys 202, 204, 206connected by bands/belts 208. These are merely examples and should notbe considered as limiting. Other suitably sized and shaped non-circularpulleys could be provided.

Although the examples described above include robot drives having onlythree coaxial drive shafts and only three motors for rotating thosecoaxial drive shafts, in alternate examples more than three drive shaftsand more than three motors could be provided.

An example embodiment may be provided in an apparatus comprising acontroller comprising a processor and a memory comprising computer code;a robot drive coupled to the controller, where the controller isconfigured to control actuation of the robot drive; a robot armconnected to the robot drive, where the robot arm comprises linksincluding an upper arm, a first forearm connected to a first end of theupper arm, a second forearm connected to a second opposite end of theupper arm, a first end effector connected to the first forearm and asecond end effector connected to the second forearm; and a transmissionconnecting the robot drive to the first and second forearms and thefirst and second end effectors, where the transmission is configured torotate the first and second forearms relative to the upper arm androtate the first and second end effectors on their respective first andsecond forearms, where the upper arm is substantially rigid such thatmovement of the upper arm by the robot drive moves both the first andsecond forearms in opposite directions, where the controller and thetransmission are configured to coordinate movement and rotation of thelinks relative to one another to move the end effectors into and out ofa station comprising: moving the first forearm relative to the upperarm, while the upper arm remains substantially stationary, to move thefirst end effector into an entrance path of the station, andsubsequently rotating the upper arm and the first forearm to move thefirst end effector along the entrance path in a substantially straightline into the station.

The robot drive may comprise a plurality of motors and a plurality ofcoaxial drive shafts, where a center of the upper arm is mounted to afirst one of the drive shafts. The plurality of coaxial drive shafts maycomprise only three coaxial drive shafts and the plurality of motors maycomprise only three motors for axially rotating the three coaxial driveshafts. The upper arm may have an effective length between the center ofthe upper arm and the first drive shaft which is substantially equal toan effective length of the first forearm between the upper arm and thefirst end effector. The transmission may comprise a first drive beltarrangement connecting a second one of the drive shafts to the firstforearm and a second drive belt arrangement connecting the first forearmto the first end effector, where the second drive belt arrangement maycomprise a variable transmission belt drive with at least onenon-circular pulley. The transmission may comprise a third drive beltarrangement connecting a third one of the drive shafts to the secondforearm and a fourth drive belt arrangement connecting the secondforearm to the second end effector, where the fourth drive beltarrangement may comprise a variable transmission belt drive with atleast one non-circular pulley. The transmission may comprise a firstmechanical connection of the first end effector with the first forearmand a second mechanical connection of the second end effector with thesecond forearm which each may comprise a band drive having at least onenon-circular pulley, and each of the first and second mechanicalconnections, including their at least one non-circular pulley, areconfigured to limit movement of the first and second end effectors ontheir respective first and second forearm such that the mechanicalconnections allow only straight movement of the first end effectorrelative to the drive when both the upper arm is rotated and the firstforearm is rotated relative to the upper arm. The controller and thetransmission may be configured to coordinate movement and rotation ofthe links relative to one another to provide a first translation motionof the first end effector in a lateral direction into an entrance pathof a substrate processing module while the upper arm remainssubstantially stationary and a subsequent second translation motion ofthe first end effector, angled relative to the first translation motion,when both the first forearm and the upper arm are rotated to move thefirst end effector along the entrance path in the substantially straightline into the station.

An example method may comprise connecting a controller to a robot drive;connecting an upper arm to a first drive shaft of the robot drive;connecting a first forearm to an end of an upper arm; connecting asecond forearm to an opposite end of the upper arm; connecting a firstend effector to the first forearm; connecting a second end effector tothe second forearm; connecting a first transmission belt arrangementbetween a second drive shaft of the robot drive and the first forearm;connecting a second transmission belt arrangement between the firstforearm and the first end effector, where the second transmission beltarrangement is configured to rotate the first end effector relative tothe first forearm when the first forearm is rotated relative to theupper arm, where the controller and the transmission belt arrangementsare configured to coordinate movement of the upper arm and the firstforearm on the upper arm relative to each another to move the first endeffector into a station comprising: a first path comprising moving thefirst forearm relative to the upper arm, while the upper arm remainssubstantially stationary, to move the first end effector into a startinglocation of a second entrance path for the station, and the secondentrance path comprising subsequently rotating the upper arm and thefirst forearm on the upper arm to move the first end effector along thesecond entrance path in a substantially straight line into the station.

The robot drive may comprise a plurality of motors and a plurality ofcoaxial drive shafts, where a center of the upper arm is mounted to afirst one of the drive shafts, where rotating the upper arm may compriserotating the upper arm about the center of the upper arm. The pluralityof coaxial drive shafts may comprise only three coaxial drive shafts andthe plurality of motors may comprise only three motors which axiallyrotate the three coaxial drive shafts. The upper arm may have aneffective length between the center of the upper arm and the first driveshaft which is substantially equal to an effective length of the firstforearm between the upper arm and the first end effector. The connectingof the first transmission belt arrangement may comprise connecting thesecond drive shaft to the first forearm by a first belt and a first setof pulleys, where the connecting of the second transmission beltarrangement may comprise connecting the first forearm to the first endeffector by a second belt and a second set of pulleys, and where thesecond set of pulleys may comprise at least one non-circular pulley toprovide a variable transmission belt drive. The method may furthercomprise connecting a third drive shaft of the robot drive to the secondforearm by a third belt and a third set of pulleys, connecting thesecond forearm to the second end effector by a fourth belt and a fourthset of pulleys, and where the fourth set of pulleys may comprise atleast one non-circular pulley to provide a variable transmission beltdrive. The second transmission belt arrangement may comprise amechanical connection of the first end effector with the first forearmwhich comprises a band drive having at least one non-circular pulley,and the mechanical connection, including the at least one non-circularpulley, may limit movement of the first end effectors on the firstforearm such that the mechanical connection allows only straightmovement of the first end effector relative to the drive when both theupper arm is rotated and the first forearm is rotated relative to theupper arm.

An example method may comprise moving a first end effector along a firstpath from a first location to a second location, where the secondlocation is a start of a subsequent second substantially straightentrance path into a substrate processing module, where the first endeffector is connected to an end of a first forearm of a robot arm, wherethe first end effector is moved along the first path by rotating thefirst forearm on an upper arm of the robot arm by a robot drive whilethe upper arm remains substantially stationary, and rotating the firstend effector relative to the first forearm as the first forearm isrotated on the upper arm, where the robot arm comprises a transmissionbelt arrangement connected between the first end effector and the firstforearm to automatically mechanically rotate the first end effectorrelative to the first forearm as the first forearm is rotated on theupper arm; and moving the first end effector from the second locationinto the substrate processing module along the second substantiallystraight entrance path, where the second substantially straight entrancepath is maintained by rotating the upper arm by the robot drive to movethe first forearm towards the substrate processing module andsimultaneously rotating the first forearm on the upper arm while thetransmission belt arrangement automatically mechanically rotates thefirst end effector relative to the first forearm, as the first forearmis rotated on the upper arm, to maintain the first end effector in asubstantially straight line into the substrate processing module.

The robot drive may comprise a plurality of motors and a plurality ofcoaxial drive shafts, where a center of the upper arm is mounted to afirst one of the drive shafts, where rotating the upper arm may compriserotating the upper arm about the center of the upper arm. The pluralityof coaxial drive shafts may comprise only three coaxial drive shafts andthe plurality of motors comprises only three motors which axially rotatethe three coaxial drive shafts. The upper arm may have an effectivelength between the center of the upper arm and the first drive shaftwhich is substantially equal to an effective length of the first forearmbetween the upper arm and the first end effector. The transmission beltarrangement may comprise a first belt and a first set of pulleys, andwhere the first set of pulleys may comprise at least one non-circularpulley to provide a variable transmission belt drive when the first endeffector is rotated on first forearm.

An example embodiment may be provided in an apparatus comprising meansfor moving a first end effector along a first path from a first locationto a second location, where the second location is a start of asubsequent second substantially straight entrance path into a substrateprocessing module, where the first end effector is connected to an endof a first forearm of a robot arm, where the first end effector is movedalong the first path by rotating the first forearm on an upper arm ofthe robot arm by a robot drive while the upper arm remains substantiallystationary, and rotating the first end effector relative to the firstforearm as the first forearm is rotated on the upper arm, where therobot arm comprises a transmission belt arrangement connected betweenthe first end effector and the first forearm to automaticallymechanically rotate the first end effector relative to the first forearmas the first forearm is rotated on the upper arm; and means for movingthe first end effector from the second location into the substrateprocessing module along the second substantially straight entrance path,where the second substantially straight entrance path is maintained byrotating the upper arm by the robot drive to move the first forearmtowards the substrate processing module and simultaneously rotating thefirst forearm on the upper arm while the transmission belt arrangementautomatically mechanically rotates the first end effector relative tothe first forearm, as the first forearm is rotated on the upper arm, tomaintain the first end effector in a substantially straight line intothe substrate processing module.

It should be understood that the foregoing description is onlyillustrative. Various alternatives and modifications can be devised bythose skilled in the art. For example, features recited in the variousdependent claims could be combined with each other in any suitablecombination(s). In addition, features from different embodimentsdescribed above could be selectively combined into a new embodiment.Accordingly, the description is intended to embrace all suchalternatives, modifications and variances which fall within the scope ofthe appended claims.

1-20. (canceled)
 21. An apparatus comprising: a robot arm configured tobe connected to a robot drive, where the robot arm comprises linksincluding an upper arm, a first forearm connected to a first end of theupper arm, a second forearm connected to a second opposite end of theupper arm, a first end effector rotatably connected to a distal end ofthe first forearm and a second end effector rotatably connected to adistal end of the second forearm; and a transmission connected to thefirst forearm and the second forearms, where the transmission isconfigured to connect the robot drive to the first forearm and thesecond forearms, where the transmission is configured to separatelyrotate the first forearm relative to the upper arm and the secondforearm relative to the upper arm, where the transmission is configuredto connect the robot drive to the first end effector and the second endeffector, where the transmission is configured to separately rotate thefirst end effector relative to the first forearm and the second endeffector relative to the second forearm, where the upper arm issubstantially rigid such that movement of the upper arm by the robotdrive moves both the first and second forearms, where the upper armcomprises a general V shape with a base of the V shape configured to beconnected to the robot drive, where the general V shape of the upper armcomprises a first arm section extending from the base and a second armsection extending from the base, where the first and second arm sectionsof the upper are extend from the base at an acute angle relative to eachother, where the first end of the upper arm is an end of the first armsection and the second end of the upper arm is an end of the second armsection.
 22. The apparatus as in claim 21 further comprising: acontroller comprising a processor and a non-transitory memory comprisingcomputer code, where the robot drive is coupled to the controller, wherethe controller is configured to control actuation of the robot drive,where the controller and the transmission are configured to coordinatemovement and rotation of the links relative to one another to move theend effectors into and out of one or more stations comprising: rotatingthe upper arm about the robot drive, where both the first and secondforearms are rotated about the robot drive at a same time, and rotatingthe first forearm relative to the upper arm, while the upper arm isrotated about the robot drive, to move the first end effector into anentrance path of one of the one or more stations, where the controllercauses the second forearm to not be moved relative to the upper armwhile the upper arm is rotated about the robot drive such that thesecond forearm is not rotated relative to the upper arm as the firstforearm is moved into the entrance path of the station.
 23. Theapparatus as in claim 22 where the robot drive comprises a plurality ofmotors and a plurality of coaxial drive shafts, where the base is acenter of the upper arm mounted to a first one of the drive shafts. 24.The apparatus as in claim 23 where the plurality of coaxial drive shaftscomprises only three coaxial drive shafts and the plurality of motorscomprises only three motors for axially rotating the three coaxial driveshafts.
 25. The apparatus as in claim 23 where the upper arm has aneffective length between the base of the general V shape and the firstforearm which is substantially equal to an effective length of the firstforearm between the upper arm and the first end effector.
 26. Theapparatus as in claim 23 where the transmission comprises a first drivebelt arrangement connecting a second one of the drive shafts to thefirst forearm and a second drive belt arrangement connecting a third oneof the drive shafts to the second forearm.
 27. The apparatus as in claim21 where the transmission comprises a band drive having at least onenon-circular pulley.
 28. The apparatus as in claim 21 where thecontroller and the transmission are configured to coordinate movementand rotation of the links relative to one another to provide a straightline motion path of a substrate holding area on the first end effectorin a direction into the entrance path of the station.
 29. A methodcomprising: connecting an upper arm to a first drive shaft of a robotdrive; connecting a first forearm to a first end of the upper arm;connecting a second forearm to an opposite second end of the upper arm;connecting a first end effector to the first forearm at a rotatableconnection; connecting a second end effector to the second forearm at arotatable connection; connecting a first transmission belt arrangementbetween a second drive shaft of the robot drive and the first forearm;connecting a second transmission belt arrangement between a third driveshaft of the robot drive and the second forearm; where the upper arm issubstantially rigid such that movement of the upper arm by the robotdrive moves both the first and second forearms, where the upper armcomprises a general V shape with a base of the V shape being connectedto the robot drive, where the general V shape of the upper arm comprisesa first arm section and a second arm section extending from the base atan acute angle relative to each other, where the first end of the upperarm is an end of the first arm section and the second end of the upperarm is an end of the second arm section.
 30. The method of claim 29further comprising: connecting a controller to the robot drive, wherethe controller and the transmission belt arrangements are configured tocoordinate movement of the upper arm and the first forearm on the upperarm relative to each another to move the first end effector into astation comprising: rotating the upper arm about the robot drive, whereboth the first and second forearms are rotated about the robot drive,and moving the first forearm relative to the upper arm, while the upperarm is rotated about the robot drive, to move the first end effectorinto an entrance path of the station, where the controller causes thesecond forearm to not be moved relative to the upper arm while the upperarm is rotated about the robot drive such that the second forearm is notrotated relative to the upper arm as the first forearm is moved into theentrance path of the station.
 31. The method of claim 29 where the robotdrive comprises a plurality of motors and a plurality of coaxial driveshafts, where the base of the upper arm is mounted to a first one of thedrive shafts.
 32. The method of claim 31 where the plurality of coaxialdrive shafts comprises only three coaxial drive shafts and the pluralityof motors comprises only three motors for axially rotating the threecoaxial drive shafts.
 33. The method of claim 31 where the upper arm hasan effective length between the base of the upper arm and the firstforearm which is substantially equal to an effective length of the firstforearm between the upper arm and the first end effector.
 34. The methodof claim 31 where the first transmission belt arrangement comprises aband drive having at least one non-circular pulley.
 35. The method ofclaim 31 where the controller and the transmission belt arrangements areconfigured to coordinate movement and rotation of the links relative toone another to provide a straight line motion path of a substrateholding area on the first end effector in a direction into the entrancepath of the station.
 36. A method comprising: moving an upper arm of arobot arm by a robot drive, where the upper arm is rotated by the robotarm, where the robot arm comprises links including the upper arm, afirst forearm connected to a first end of the upper arm, a secondforearm connected to a second opposite end of the upper arm, a first endeffector rotatably connected to a distal end of the first forearm and asecond end effector rotatably connected to a distal end of the secondforearm, where the upper arm is substantially rigid such that movementof the upper arm by the robot drive moves both the first and secondforearms, where the upper arm comprises a general V shape with a base ofthe general V shape connected to the robot drive, where the general Vshape of the upper arm comprises a first arm section and a second armsection extending from the base at an acute angle relative to eachother, where the first end of the upper arm is an end of the first armsection and the second end of the upper arm is an end of the second armsection; rotating the first forearm on the upper arm, while the upperarm is rotated about the robot drive, to move the first end effectorinto an entrance path of a station, and where the second forearm isprevented from being moved relative to the upper arm while the firstforearm is rotated about the upper arm such that the second forearm isnot rotated relative to the upper arm as the first forearm is moved intothe entrance path of the station.